DECREASE IN VECURONIUM INFUSION DOSE REQUIREMENTS BY NICARDIPINE IN HUMANS

This study was designed to analyze quantitatively the interaction of n icardipine with vecuronium using a constant infusion technique. Forty- seven patients undergoing elective otolaryngeal surgery were anestheti zed with isoflurane (1% end-tidal) and nitrous oxide (67%). Patients w ere randomly assigned to receive one of four doses of nicardipine (0, 1, 2, and 3 mu g.kg(-1).min(-1)). Vecuronium infusion dose requirement was determined as a constant infusion rate which maintained 90% depre ssion of control twitch tension. Nicardipine significantly decreased t he vecuronium requirement in a dose-dependent manner, i.e., the vecuro nium doses were 0.70 +/- 0.03, 0.55 +/- 0.04, 0.42 +/- 0.04, and 0.37 +/- 0.05 mu g.kg(-1).min(-1) at nicardipine doses of 0, 1, 2, and 3 mu g.kg(-1).min(-1), respectively. Nicardipine also reduced both the pla sma concentration of vecuronium to maintain the 90% depression and the total plasma clearance of vecuronium. The reversal of the vecuronium effect with neostigmine was not influenced by nicardipine. The results indicate that the vecuronium infusion dose requirements are reduced a s much as 53% by a clinical dose of nicardipine.